Two pilots whose jets crashed into a Scottish mountain were told to drop altitude moments before the tragedy, a court martial has heard.

Flight Lieutenant Malcolm Williams, accused of causing the deaths of the US airmen, was said to have made the instruction to the F15s as he was attempting to transfer air traffic control from his base at RAF Leuchars to RAF Lossiemouth.

Defence witness Wing Commander Christopher Foster also said Mr Williams had been confused during the handover as a result of "factors out with his control".

It (the handover) was not going well at all. An air traffic control handover is a well-regimented set of charges and responses.

Wing Commander Christopher Foster

Wing Cdr Foster, based at the Swanwick joint civil and military air control centre, near Southampton, was giving evidence on the 16th day of the case.

It is alleged Mr Williams told the Americans to fly 2,500ft below the safety limit in a snowstorm.

The two pilots died when their single-seater jets crashed into Ben Macdui in the Cairngorms on 26 March, 2001.

Appearing before a court martial in Helensburgh, Argyll and Bute, Mr Williams denied the charge.

He also denies an alternative charge of professional negligence.

Radar information

Michael Jones QC, for the defence, asked Wing Cdr Foster if he could explain why Mr Williams had asked the pilots to descend to 4,000ft, based on a transcript of their conversation.

Wing Cdr Foster replied: "I can think of something that could be construed as a logical choice of 4,000ft.

"In the circumstances of this transcript Williams has already initiated a handover to Lossiemouth whilst the aircraft were at flight level 80 (8,000ft).

Lt Col Hyvonen was the lead pilot

"The pilot of Bite 21 (the lead jet's call sign) had previously asked how far north they could be seen on radar in order to maintain their radar information
service and having initiated the handover to Lossiemouth the aircraft requested a descent.

"At the same time the aircraft was rapidly approaching the edge of Leuchars normal 40-mile radar range.

"The physical distance between Leuchars and Lossiemouth is in the order of 80 miles so an initial descent to 4,000ft should be sufficient to keep an aircraft more or less in radar coverage of both units."

Mr Jones asked Wing Cdr Foster how well the handover seemed to be going from the initial exchanges on the transcript.

'Eye off the ball'

Wing Cdr Foster said: "It was not going well at all.
An air traffic control handover is a well-regimented set of charges and responses.

"The things going on from Lossiemouth were not what I would expect."

Wing Cdr Foster told the court martial that the air traffic controller from Lossiemouth had answered the initial call from Leuchars by stating his name.

He said that could not have happened.

Captain Kirk Jones died in the accident

Wing Cdr Foster also said Lossiemouth should not have asked Leuchars whether the jets were in cloud and whether they were military aircraft.

On the effect that this information would have on Mr Williams, Wing Cdr Foster said: "From the Leuchars controller's perspective, in jargon language, it could take his eye off the ball."

Mr Jones also asked Wing Cdr Foster about the American pilots' use of the term "minimum vectoring altitude".

He said it was a term that would not have been understood by Mr Williams.

Wing Cdr Foster was then asked why Mr Williams had not queried it with the pilot.

He said: "The most likely explanation is that he did not hear it and, because he had two conversations going on simultaneously, the words may just not have
registered with him."